When the driver of a motor vehicle that is equipped with foglamps, a large truck for example, encounters fog, he or she will turn on the foglamps. In certain vehicles, this will also cause the low-beam headlamps to illuminate. Alternatively, it may be mandatory for the low-beams to be on in order for the foglamps to illuminate when the latter are switched on.
The concurrent use of both foglamps and headlamps, particularly the low-beam headlamps, to illuminate the driver's field of view in fog may create a condition where upwardly shining portions of the headlight beams striking fog create glare that impairs the driver's view. While foglamps are typically aimed to shine lower than low-beam headlamps for illuminating the forward field of view, especially the road surface farther ahead, the presence of glare from the headlamps can obstruct, or to some extent impair, the driver's view that the lighting system is intended to illuminate.
Consequently, it is believed that improvements for reducing headlight glare in such circumstances would be desirable.